Sudden cardiac arrest in apical hypertrophic cardiomyopathy

We present two cases of cardiac arrest, presumably attributable to apical hypertrophic cardiomyopathy (HCM). The first case was a 37-year-old Asian man known to have an apical HCM and was successfully resuscitated from an "out of hospital" ventricular fibrillation arrest. He underwent an electrophysiological study that was unable to induce tachyarrhythmias, which may not be surprising. He did receive an automated internal cardioverter defibrillator (AICD) in compliance with his class I indication for an implantable defibrillator. The second patient was an 86-year-old Caucasian woman with a cardiac history significant for apical HCM, coronary artery disease, diastolic heart failure, and monomorphic ventricular tachycardia. She underwent electrophysiological testing for frequent dizziness and monomorphic ventricular tachycardia of a right ventricular origin was induced. She received an AICD for sudden cardiac death prevention. Though lethal ventricular arrhythmias have been reported in patients with apical HCM, the prevailing consensus is that the prognosis of apical HCM is benign. Whether these accounts are truly exceptional occurrences for this rare and conventionally regarded benign condition or whether they represent an under-appreciated risk for sudden cardiac arrest is an intriguing question.